In optoelectronic devices, light rays are absorbed and generate charge carriers within the device. These charge carriers typically are desired to be generated within a particular light ray absorption region, which can be defined by a depth within the device, such that they can be collected near the surface of the device.
Charge carriers generated deeper than the depth of this region can be thought of us undesirable noise. Conventional approaches to dealing with these charge carriers often relate to transporting them to the surface by extended electric fields or annihilating them by the targeted introduction of recombination centers. The former is not suitable in all situations, such as those with regions that must remain free of electrical fields for physical reasons, and is also limited by available voltage, while the latter reduces internal quantum efficiency and can be technically difficult to realize at very high impurity atom densities. Reduced quantum efficiency in turn can affect devices dimensions, and increased complexity and technological challenges can increase costs, which are undesired.